1. Field of the Invention
The present invention relates to a lens driving device with 3D elastic support structure, and more particularly, to a lens driving device using a voice coil motor (VCM).
2. Description of the Prior Art
Miniature cameras are becoming increasingly common in mobile electronic devices such as mobile phone and tablet PC. There is a constant drive to improve performance of such cameras, while still maintaining the same envelope. Demands on improvements to performance of such miniature cameras are constant, as are demands for continued miniaturization, given the added features and devices added to such mobile electronic devices. In particular, high image quality requires the lens motion along the optical axis to be accompanied by minimal parasitic motion in the other degrees of freedom, particularly tilt about axes orthogonal to the optical axis. This requires the suspension mechanism to be stiff to such parasitic motions. However, given the need to control the lens position with a resolution of 1 micron, such suspension mechanisms must account for friction.
FIG. 15 is a schematic view showing the main structure of a conventional lens driving device for a voice coil motor (VCM). For the convenience of description, some minor parts of the lens driving device are not shown. As shown in FIG. 15, the lens driving device 15 includes mainly an first upper plate spring 1511, an second upper plate spring 1512, a lens holder 152, a focusing coil 153, an optical image stabilizer (OIS) coil structure 154, and a flexible printed circuit 155.
The lens driving device 15 further includes two first suspension wires 1561˜1562 and two second suspension wires 1563 and 1564. The first suspension wires 1561 and 1562 are respectively connected electrically to the flexible printed circuit 155 with one end and connected electrically to the first upper plate spring 1511 with the other end. The second suspension wires 1563 and 1564 are respectively connected electrically to the flexible printed circuit 155 with one end and connected electrically to the second upper plate spring 1512 with the other end. To be noted, the first upper plate spring 1511 and the second upper plate spring 1512 are disposed separately to each other and therefore have no structural connection.
FIG. 16 is a partially enlarged top view showing the electrical connection between the focusing coil and the upper plate spring of the lens driving device of FIG. 15. As shown in FIG. 16, the focusing coil 153 is further connected electrically to the first upper plate spring 1511 with a soldered portion 16. Besides, it is understandable that the focusing coil 153 is also connected electrically to the second upper plate spring 1512 with another soldered portion (not shown).
FIG. 17 is a partially enlarged bottom view showing the electrical connection between the flexible printed circuit and the suspension wire and the connection between the upper plate spring and the suspension wire, of the lens driving device of FIG. 15. As shown in FIG. 17, the flexible printed circuit 155 is connected electrically to one end of the first suspension wire 1561 with a soldered portion 171, and the first upper plate spring 1511 is further connected electrically to the other end of the first suspension wire 1561 with a soldered portion 172. Besides, not shown in the figures, it is understandable that the flexible printed circuit 155 is connected electrically to one end of the second suspension wire 1562 with a soldered portion 17, and the first upper plate spring 1511 is further connected electrically to the other end of the second suspension wire 1562 with another soldered portion.
Similarly, not shown in the figures, the flexible printed circuit 155 is connected electrically to one end of the second suspension wire 1563 with a soldered portion, and the second upper plate spring 1512 is further connected electrically to the other end of the second suspension wire 1563 with another soldered portion. Also, the flexible printed circuit 155 is connected electrically to one end of the second suspension wire 1564 with a soldered portion, and the second upper plate spring 1512 is further connected electrically to the other end of the second suspension wire 1564 with another soldered portion.
Due to the use of the soldered portions, which increases the process difficulty and the weight of device, there is a strong desire, for a given size of camera, to fit bigger lenses and image sensors to improve image quality, and hence there is a desire to reduce the parts number and to eliminate the soldering process for connecting the suspension wire with the upper plate springs.